Danny Boyle has said he would gnaw his own arm off if he had to, to save his life.

The Oscar-winning director's new film 127 Hours is based on the true story of mountain climber Aron Ralston, who hacked off his own arm with a penknife after it became trapped under a rock, leaving him stranded in a Utah canyon for five days with little food and water.

Danny insisted at a press conference ahead of the film's closing gala premiere of the BFI London Film Festival he would do the same thing in his situation.

The director said: "One of the extraordinary things about the story is when it's told in a superficial way people say 'Ooh, I could never do that'.

"We'd all do it and if you didn't have a knife you'd chew it off, which is an extraordinary thing to say but animals do it all the time.

"When everything is stripped away, yes you would, I think."

James Franco, who plays Aron in the film, revealed how when he first met the mountaineer he learned it was his connection to his family that got him through his ordeal.

James said Aron asked him why he wanted to play him.

"I said 'I really admire the strength that you had to get through it on your own, I think it's an incredible example of human will'. And he corrected me a little bit. He said 'Well no actually it was my connection to my family, and that allowed me to get through those five days and get myself out of there,'" James explained.